In the past decade, the semiconductor industry has played a very important role in the global economy, by which exploitation and application of various kinds of micro electro mechanical products are promoted along with development of the semiconductor technology. However, as the line width and line pitch processed for various kinds of products are continuously decreased to smaller than 100 nanometers, the current photo-lithography technology encounters a physical problem in optical imaging, and the fabrication difficulty and costs of fabrication equipment are also greatly increased. Although a next-generation lithography technology has been proposed, it still has problems of high equipment costs and low yields. Consequently, the most popular lithography technology at present is nanoimprint lithography (NIL) technology, which is not restricted by diffraction limitation of optical lithography, and has advantages such as high lithography resolution, fast fabrication speed, low production costs and so on.
Generally, thermal compression molding process and ultraviolet curing process are primary nanoimprint technologies at present. The thermal compression molding process is to imprint mold patterns to a substrate coated with a polymer material under high temperature and high pressure, and the ultraviolet curing process uses ultraviolet irradiation to cure and mold microstructures under normal temperature and normal pressure. As the molding techniques and fabrication conditions of these two processes are different, corresponding independent system modules thereof are mostly provided in the current design of devices. The related prior art patents include WO 2004/016406, U.S. Pat. No. 6,482,742, and WO 2004/114017A1, etc.
For example, WO 2004/016406 discloses a microimprint/nanoimprint device using the ultraviolet curing technology as shown in FIGS. 4A and 4B. Referring to FIG. 4A, the microimprint/nanoimprint device comprises a power source 301, an imprint unit carrier 302, an imprint unit 303, an ultraviolet module 304, a mold 305, a substrate 306, a substrate carrier 307, a movable feeding platform 308, and a platform carrier 309. As shown in FIG. 4B, the imprint unit 303 comprises a self adjusting mechanism 3031 for adjusting parallelism between the mold 305 and the substrate 306. The ultraviolet module 304 comprises an ultraviolet source 3041 and a refractor 3042.
During imprinting, the power source 301 drives the imprint unit 303 to move downwardly, allowing the mold 305 to be in contact with the substrate 306, wherein the self adjusting mechanism 3031 adjusts and keeps parallelism between the mold 305 and the substrate 306. The ultraviolet source 3041 of the ultraviolet module 304 provides ultraviolet energy with appropriate power that is transferred via the refractor 3042 so as to cure a molding material between the mold 305 and the substrate 306.
However, since the power source and the ultraviolet source are located at the same side of the microimprint/nanoimprint device, in order to prevent any interference in arrangement between the ultraviolet source, the power source and other components such as a mold clamping mechanism, it is necessary to employ a complicated design of optical mechanism allowing ultraviolet from the ultraviolet source to be laterally inputted and then transferred via the refractor such that the ultraviolet energy can be transmitted to the molding material. This not only complicates the design of ultraviolet source but also greatly increases the device costs.
Further, the microimprint/nanoimprint device may only be applied to a small area imprinting process. In the case for achieving large area imprinting, the microimprint/nanoimprint device must repeatedly perform the imprinting process periodically. Consequently, this conventional technology prolongs a product fabrication period of time and may affect the product yields directly due to errors of alignment precision between the periods.
Another microimprint/nanoimprint device capable of performing both thermal compression molding and ultraviolet curing processes has been proposed as in U.S. Pat. No. 6,482,742 for example. U.S. Pat. No. 6,482,742 discloses a fluid pressure imprint lithography device as shown in FIGS. 5A and 5B. The fluid pressure imprint lithography device comprises a sealing chamber 401, a fluid entrance 402 formed at two opposite sides of the sealing chamber 401 respectively, a mold 403, a substrate 405 coated with a molding material 404, a sealing envelope 406 for encapsulating the mold 403 and the substrate 405, a heating unit 407 provided in the sealing chamber 401, and a light penetrable window 408 provided at a top side of the sealing chamber 401.
During imprinting, the mold 403 and the substrate 405 are encapsulated by the sealing envelope 406 and then placed into the sealing chamber 401. The substrate 405 is heated to a predetermined molding temperature by the heating unit 407, and then a fluid (not shown) is filled from the fluid entrances 402 to exert pressure to the mold 403 so as to perform the thermal compression molding process. When the fluid exerts pressure to the mold 403, an external ultraviolet source (not shown) may be used to irradiate the molding material 404 on the substrate 405 via the light penetrable window 408 to perform the ultraviolet curing process. Therefore, an imprint molding process of nanostructures can be performed by such design having both functions of thermal compression molding and ultraviolet curing.
However, when employing the fluid pressure imprint lithography device disclosed in U.S. Pat. No. 6,482,742, it must spend time on changing system modules, thereby increasing the device costs. Further, the mold and the substrate should be stacked and sealed before imprinting, and the sealing envelope should be removed after imprint molding to unseal the mold and the substrate and perform a mold releasing process. This increases processing costs before and after imprinting, and makes control of the fabrication processes not continuous, thereby prolonging a molding period and not favorable for mass production.
Moreover, the sealing envelope generally has relatively poorer light penetrability, such that when ultraviolet needs to go through the light penetrable window and the sealing envelope, the ultraviolet energy is apt to be absorbed during transmission or even becomes scattered. As this conventional technology cannot control the provided ultraviolet energy and cannot obtain a uniformly imprinted product, the molding quality of the molding material would be affected.
Therefore, it is greatly desirable to develop a microimprint/nanoimprint device, capable of solving the problems in the foregoing conventional technology such as high costs, low yields, poor quality and unfavorable for mass production, which are caused by the drawbacks such as having a complicated design of light source mechanism, high equipment costs, small imprinting area, increased processing costs, discontinuous control of fabrication processes, a prolonged molding period, and difficulty in controlling the molding quality.